Static eliminator for radio equipment



R. W. BROWN Aug. 6, 1929. i

STATI@ ELIMINATOR FOR RADIO EQUHMENT Filed Jan. 17, 192e Cil Patented Aug. 6, 1929.

ROLAND W. BR'OVN, OF NW YORK, N. Y.

STATIC ELIMINATOR FOR RADIO EQUI'IMENT.

Application filed January 17, 1928.

This invention relates to radio static filtering devices.

Among the objects of the invention is to provide a device for thoroughly eliminating static from radio receivingsets and similar apparatus which device may comprise a plurality of separate independent unit-s inserted in the circuit of the receiving set at such points as may be most advantageous and preferably, for example, in the lead extending to the antenna and also in the ground circuit.

Another object of this invention is the provision of a device of the character described wherein an improved preparation for filtering static from a radio receiving apparatus or the like comprises preferably a woody material, the latter being for highest efficiency of a finely divided form and having extended electrical surface contact with an electrical conductor of a proper circuit.

A further'object of the invention is to produce a device of the species mentioned wherein an electrical circuit associated with a radio receiving set may include therein a finely divided material, such for example, as wood, which material is impregnated with an electrical conductingsalt.

lVith the foregoing and other objects in view the invention consists in the arrangement and combination' of parts hereinafter described and claimed, and while the invention is not restricted to the exact details of construction disclosed or suggested herein, still for the purpose of illustrating a practical embodiment thereof reference is had to the accompanying drawings in which like referencecharacters designate the same parts in the several views, and in which- Figure 1 is a diagrammatic view in elevation of an embodiment of the invention.

Fig. 2 is a longitudinal cross section of an aerial filter embodying the invention.

Fig. 3 is a cross section taken on the line 3 3 of Fig. 2.

Fig. 4 is a longitudinal cross section with a part removed and showing an embodiment of the invention in the ground filter.

Fig. 5 is a cross sectional View taken on the line 5 5 of Fig. 4.

Referring in detail to the drawings, 1() denotes a device embodying the invention, said device may include a radio receiving set 11, an antenna 12, and a ground 18. The receiving set is connected at binding Serial No. 247,278.

posts 141 and 15 to the antenna. and ground respectively by conductor wires 1G and 17. lnterposcd in the aerial and ground circuits are filters 18 and 1S) respectively. These devices are of simple and compact construction and may be mounted in any convenient manner so as to be neat and inconspicuous.

The aerial filter 18 is mounted upon a bracket 18 to which it is engaged in any suitable manner as, for example, by means of straps 20.- The latter preferably pass around an elongated tubular container 21. The said container 2l is preferably made of any insulating material. such as paper, o r the like. Coaxia-lly mounted therein is an inner tubular .member '22, having its side wall spaced from the sides of the chamber 21, but extending substantially from end to end of the same. The inner member 22 is filled with a finely divided material 22, preferably sawdust, which is impregnated with electrically conductive salt solution, as will be described hereinafter. The member 22 formed with enlarged ends 28. An electric terminal 24 is inserted at one of said ends and extends through an adjacent end Vall of the chamber 21. ln the other ond of said container is placed a terminal in the form of a stopper. The said terminals are in contact with the conductive static absorbing material 22W, which forms part of the electric circuit.

The said inner tube 22 is preferably made of soft or hard rubber, glass, wood, or the like, and in practical use is approximately two feet long. As illustrative of the pro portions of the material used in the inner tube, I otler the following: To four ounces of pure water, I add two tea spoonsful of (heaped) Rochelle salts, and about one spoonful of (heaped) table salt. lVhen the above have been thoroughly mixed, I soak about ten spoonsful of wood sawdust Yin the solution, and add a tea spoonful of glycerine to keep the solution from drying too soon. The sawdust is then packed solidly into the inner filter tube.

From the terminal 25, a conductor 2G extends along the tube 22 to an external terminal 27. Preferably the said conductor consists of a copper' wire wound around the filter tube 22, with its coils in spaced relation. The said wire may be of No. 22 gage, uninsulated, and I may use 22 or 23 feet of it. About the said filter tube is packed dry sawdust 28. rl`hus the wire coil has extended surface contact with the sawdust, the latter furnishing the final stage in filtering out static, interference, and noises.

lt is thus seen that I have provided a filtering device for use in conjunction with the antenna of a radio receiving apparatus which includes an extended circuit having improved absorption features. The said circuit is seen to include a woody material as an essential part ofit, and also various auxiliary features such, for example, as the electrically conductive solution used with the sawdust in the inner tube 22, and also the outer coil conductor 26. In the device as shown current vfirst flows in one direction through the material in the inner tube and then finally in. a reverse direction through the coil extending along the same tube. Inthis way the economy of space is effected and absorption of static is provided for in two separate stages, the second of which occurs in connection with the dry sawdust between the inner and outer tubes.. The filter 19 applied in the ground circ-uit includes a wooden core of thin rod-like form extending coaxially through a tubular casing or chamber 3l in spaced relation to the side wall thereof and in proximity to the end walls of the chamber. Terminals 32 and 33 may be formed with integral screw threaded shanks 34 which extend into the end portions of the said Core so as to mount the same within the casing. A coil of conductive material 35 such, for example, as copper wire is wound around the said core and engages at its ends the said terminals. The said wire is preferably of No. 22 gage, uninsulated, and the coils thereof are spaced uniformly along the inner cere so that approximately- 22 or 23 feet of the same are required. Packed around the said inner core and fully occupying` the space between the latterand the outer casing 3l is a quantity of sawdust 36 used to take up theground static. The casing 3l is preferably made of a non-conducting material as, for example, rubber, glass, or wood. The same operates in an efficient manner conjointly with the sawdust 36 to eliminate interference in radio receiving sets and all those noises which detract from the quality of the music. Y It is thus seen that I have provided a device which is simple in construction and operatiom inexpensive to manufacture, and practical and efficient to a high degree in use. By this invention the several objects herein set forth are fully achieved and the pleasure of the user of a radio set greatly enhanced.

I claim: Y

l. A device of the character described, including an inner container of non-conducting material, a finely divided non-conducting material in. said container, saturated with a salt, said salt being electrically conductive, an electrical terminal contacting said finely divided material, an electrical conductor extending along the exterior ofA said container, an outer container surrounding the inner one, a non-conducting material in the outer container packed about the inner container andthe conductor thereon, said conductor contacting at one end Asaid finely divided material remote from said terminah and another terminal connect-ed to the other end of said conductor.

2. A device as setforth in claim l, wherein said finely divided material consists of sawdust.

3. A device of the character described, including an inner container' of'non-conducting material, a finely divided non-conducting material in said container, saturated with a salt, said salt being electrically conductive, an electrical terminal contacting said finelyV divided material, an electrical conductor extending along the exterior of said container, anouter container surrounding the inner one, a non-conducting material in the outer container packed about the inner container and the conductor thereon, said conductor contacting at one end said finely divided material remote from said terminal, and another terminal connected to the other end of said conductor, said finely divided material consisting of sawdust, and said non-conducting material in said outer container consisting of sawdust.

In testimony whereof l affix my signature.

ROLAND W BROWN.

Cil 

